Attempts have been made in the prior art to provide an emergency braking system for the air brakes of a vehicle, which will serve to prevent the runaway of the vehicle should the service air pressure of the braking system fail for any reason. Most prior art air brake emergency braking systems, however, are subject to certain disadvantages in that, in some instances, they are bulky and unduly complex. In other instances, considerable and expensive changes to the vehicle chassis are necessary in order to install the emergency braking systems. Moreover, some of the prior art emergency braking mechanisms are too expensive as to justify their installation.
Many of the prior art emergency braking mechanisms are merely auxiliary brakes which can be applied in the case of the air brakes malfunction. In other words, such prior art mechanisms do not operate automatically should the air brakes become ineffective, and there is no means to inform the operator of the vehicle in advance that the air brakes are not working. Still other prior art mechanisms act on the cam shift lever of the air brakes and cannot be applied in emergencies when the air brakes are out of adjustment.
Some of the prior art emergency braking systems can also be used for parking purposes. However, for the most part such prior art brakes can only be released by compressed air from the truck. Therefore, if such a prior art brake was installed in a trailer, there would be no way of moving the trailer unless a source of compressed air was available. The braking mechanism of the present invention has the feature in that it can be released and re-set mechanically and without the need for compressed air.
The present invention provides a relatively simple and inexpensive brake system which can be incorporated into trailers, tractors, trucks, buses or the like, and which can be easily installed in existing vehicles equipped with air brakes. The invention also provides a brake mechanism which is economical and efficient, and which rapidly and automatically sets and latches the air brakes of the vehicle whenever a failure in the service brake power system occurs, for any reason. Moreover, the invention provides a braking system which can be used for parking purposes, and which can easily be mechanically set, released and re-set.
Most heavy trucks and trailers are equipped with air brakes in which necessary pressure is built up and maintained in a storage tank by a compressor. Actuation of the brakes releases air under pressure against a diaphragm or piston in a brake chamber, which diaphram or piston is operatively connected to the brake rods of the vehicle to set its brakes. The safety braking mechanism of the present invention operates in conjunction with such a braking system and, as mentioned above, serves to set and latch the brakes of the vehicle whenever the air pressure in the air braking system falls below a predetermined threshold.
Accordingly, a primary objective of the present invention is to provide a braking mechanism which is particularly adapted for use in conjunction with motor vehicles of the type using air brakes which necessitate a source of air under pressure for their operation, the braking mechanism of the invention being adapted to set and latch the brakes of the vehicle at any time that there is insufficient air pressure from the source.
Another objective of the present invention is to provide an improved braking mechanism which is adapted to set and latch the brakes of the vehicle whenever the air braking system is in an abnormal condition, the mechanism of the invention incorporating a minimum number of parts so that it is not only subject to simple and trouble-free operation, but it also lends itself to economical mass production. Another object of the present invention is to provide such a braking system which serves to set and latch the air brakes under emergency conditions, as when the air hose is broken, or become disconnected, or is leaking; and which may also serve as a parking brake for the vehicle when there is no air pressure available.
Another objective of the invention is to provide such an emergency and parking brake mechanism which aplies a mechanical lock to the brakes when set, which is not dependent on a compressed air source which could be subject to leakage, and which has no tendency to fail when it has been set.
Yet another objective of the invention is to provide such an improved emergency and parking brake mechanism which may be mechanically released (for example, by a special tool to prevent vandalism), should it become necessary to move a parked trailer, or the like, when no source of compressed air is available.